1. Field of the Invention
The invention relates to a sheet-fed scanner capable of scanning multiple scan lines for image signal calibration, and more particularly to a sheet-fed scanner capable of scanning multiple scan lines on a calibration sheet to obtain an image signal calibration standard.
2. Description of the Related Art
Before scanning a document, a typical scanner has to scan a calibration sheet with a standard color (e.g., standard white, standard black, or the like) to obtain a calibration standard for calibrating an image signal of the scanned document.
In a conventional sheet-fed scanner, a stationary scanning module scans a document fed by a sheet-feeding mechanism and also scans a stationary calibration sheet. Thus, after the scanning module scans the calibration sheet, the data corresponding to only one scan line is obtained to serve as the calibration standard for the subsequent scanning processes. When the calibration sheet is contaminated, the data corresponding to the single scan line may have great errors such that the subsequent scanning results are influenced significantly.
Thus, it is an important subject of the invention to provide a sheet-fed scanner capable of scanning multiple scan lines on a calibration sheet to obtain a calibration standard for calibrating an image signal without distorting the calibrated image.